Intra-observer reproducibility and inter-observer agreement of Fels skeletal age assessments among male tennis players 8-16 years.

BACKGROUND: Skeletal age (SA) is an estimate of biological maturity status that is commonly used in sport-related medical examinations. This study considered intra-observer reproducibility and inter-observer agreement of SA assessments among male tennis players. METHODS: SA was assessed with the Fels method in 97 male tennis players with chronological ages (CA) spanning 8.7-16.8 years. Radiographs were evaluated by two independent trained observers. Based on the difference between SA and CA, players were classified as late, average or early maturing; if a player was skeletally mature, he was noted as such as an SA is not assigned. RESULTS: The magnitude of intra-individual differences between repeated SA assessments were d = 0.008 year (observer A) and d = 0.001 year (observer B); the respective coefficients of variation were 1.11% and 1.75%. Inter-observer mean differences were negligible (t = 1.252, p = 0.210) and the intra-class correlation coefficient was nearly perfect (ICC = 0.995). Concordance of classifications of players by maturity status between observers was 90%. CONCLUSION: Fels SA assessments were highly reproducible and showed an acceptable level of inter-observer agreement between trained examiners. Classifications of players by skeletal maturity status based on assessments of the two observers were highly concordant, though not 100%. The results highlight the importance of experienced observers in skeletal maturity assessments.

Developmental fitness curves: assessing sprint acceleration relative to age and maturity status in elite junior tennis players.

BACKGROUND: The influence of maturity-status on athletic performance is reasonably well-documented. Methodological and practical issues of assessment and lack of longitudinal data have impacted the success of various models. AIM: To develop age- and sex-specific developmental curves for sprint acceleration in elite youth tennis players and to address variation in performance relative to chronological and biological age. SUBJECTS AND METHODS: Measures of acceleration were available for 3120 elite youth tennis players aged 8-15 years attending National and Regional Talent Identification days. Variation in acceleration by chronological and estimated biological ages was evaluated in corresponding data for an independent sample of elite youth players 8.9 to 15.1 years of age. RESULTS: Acceleration varied as a function of chronological and biological age relative to developmental curves. Early maturing males and females had significantly poorer performances when acceleration was considered relative to biological age. Significant discrepancy in percentiles relative to biological versus chronological ages was also evident between early and late maturing players of each sex. CONCLUSION: Evaluating performance relative to developmental curves and maturity status may be a practical means of monitoring long-term athlete development in tennis.

Maturity-Associated Variation in Functional Characteristics Of Elite Youth Tennis Players.

PURPOSE: To evaluate relationships among skeletal maturity, body size, and functional capacities of elite junior tennis players. METHODS: Participants were 88 elite British Junior tennis players (44 male; 44 female), 8-16 years of age (12.4 } 1.9 years). Skeletal age estimated maturty. Anthropometry, grip strength, countermovement jump, squat jump, forehand agility, backhand agility, Yo-Yo, 5-m, 10-m and 20-m sprints were measured. Comparative analysis for each sex was performed, relating advanced maturers (Male: 15; Female: 29) to a combination of on-time and late maturers (Male: 29; Female: 31). ANCOVAs were used to determine absolute differences between male and female players and between the 2 maturity subgroups, with chronological age as the covariate. RESULTS: Advanced maturity afforded male players advantages in absolute measures of grip strength, speed, upper and lower body power but not in acceleration, agility or aerobic endurance. Male players were significantly taller than females in the U13-U16 age group. Advanced maturity in female players afforded advantages in absolute measures of grip strength, agility and overhead power, but not in backhand agility, aerobic endurance or squat jump power. CONCLUSION: It is important that talent identification protocols consider the maturity of youth athletes to more satisfactorily address athletic potential rather than transient physical capabilities.

Growth and maturity status of elite British junior tennis players.

Growth and maturation impact the selection, development and progression of youth athletes. Individual differences in the growth and maturity may afford a performance advantage, clouding coaches and practitioners' perceptions regarding current ability and future potential. This may result in the exclusion of talented, yet less physically gifted athletes. Participants were 91 male (n = 47) and female (n = 44) elite British Junior tennis players, 8-17 years of age (12.5 ± 1.9 years). Height and body mass were measured and compared to growth charts; hand-wrist radiographs were taken. Skeletal age (SA) was estimated with the Fels method and contrasted to chronological age (CA). Mean height and body mass of individual players ranged between the 50th and 90th centiles for age and sex. Females were advanced in SA relative to CA (0.3-0.89 years.) from 8 years. Males were average to delayed in maturation from 8 to 12 years, but advanced in SA from 14 to 16 years (0.75-1.23 years). Individual differences in growth and maturation appear to contribute towards the selection of elite junior tennis players, with a bias towards males and females who are advanced in maturation and comparatively tall and heavy for their age. This has important implications for talent identification and development.

Cross-Sectional Analysis Investigating the Concordance of Maturity Status Classifications in Elite Caucasian Youth Tennis Players.

BACKGROUND: To evaluate the concordance of skeletal age (SA) with two predicted estimates of biological maturity status in elite British youth tennis players. METHOD: Participants were 71 male and female elite youth tennis players aged 8 to 16 years. Weight, height, and sitting height were measured. SA (Fels method) was the criterion indicator of maturity status. Maturity status was predicted with two methods: predicted age at peak height velocity and percentage of predicted adult height at the time of observation. Players were classified as late, average (on time), or early maturing with each method. Concordance of classifications was evaluated with kappa coefficients and Spearman's rank order correlations. RESULTS: Kappa coefficients between maturity status classifications were low in both sexes, - 0.11 to 0.22, while Spearman's rank order correlations between maturity status classifications based on SA and the percentage of predicted mature height were moderate in males (0.35) and females (0.25), but the corresponding correlations based on predicted age at peak height velocity (PHV) varied, moderate and negative in boys (- 0.37) and low and positive in girls (0.11). Concordance of maturity status classifications based on the prediction methods and SA among tennis players was thus limited. CONCLUSIONS: Maturity status based on the percentage of predicted mature height at the time of observation correlated better with maturity status based on SA in contrast to status based on predicted age at PHV in this sample of elite youth tennis players.